"He" is Dr Julian Lewis – bane of CND, ex-infiltrator of the Labour Party, campaigner by law suit, loudspeaker and, in his own words, "street theatre" against all things Trot and pacifist.

Yesterday, Kenneth Baker, chairman of the Conservative Party, announced that Dr Lewis, 38, friend of the right-wing Freedom Association and campaigner for trade union officials to be elected, will become joint Deputy Director of the Conservative Research Department next month.

His brief is to help prepare the Tories for the next general election. "I just wonder," Meg Beresford, general secretary of CND said, "if the Tories understand what they have taken on. If he's going to be involved in running the next election it's likely to be pretty dirty." The charge makes Dr Lewis laugh.

"It depends what you mean by fighting dirty," he said. "If people cover themselves in dirt and we point it out, then you could perhaps say there is some justice in the charge."

Digging the dirt on CND, Trotskyite infiltration of Labour and running "counter-propaganda" has been Dr Lewis's speciality. A graduate of Balliol and Oxford [University] Conservative Association treasurer, he first came to prominence in the 1970s when he joined the Newham North-East Labour Party in east London to fight the far left's attempts to de-select Reg Prentice. Writs costing Labour and the Freedom Association many thousands of pounds flew as Dr Lewis exploited Labour's rule book to gain control of the constituency with tactics mirroring those of the left.

"I have always believed," he said yesterday, "that it is absolutely essential for a proper democracy to have two moderate competing political parties."

His attempt to rescue Labour from the left (his view), or exploit its divisions (Labour's view) ended in court defeat and the founding of the Coalition for Peace Through Security, a three-man band composed of himself, Edward Leigh, now the Tory MP for Gainsborough, and Tony Kerpel, now Mr Baker's political assistant.

It harassed CND in its heyday, publishing lists of left-wingers on its executive, flying banners over its demonstrations, and filming them from the air to challenge the campaign's claims on numbers.

In 1982, while playing the national anthem over a march headed by Tony Benn and Arthur Scargill against the Falklands war, Dr Lewis was briefly arrested, though not charged, for breach of the peace. All "street theatre", he said yesterday.

In 1983, he came within 2,350 votes of taking Swansea West for the Tories from Alan Williams, who described him yesterday as "my most remarkable opponent. Even for a right-wing Tory he's atypical".

Yesterday, Dr Lewis confined himself to saying: "I have always been a strong supporter of Mrs Thatcher" – and that he hoped once again to help rescue Labour at the next election by defeating them.

"Every time they lose, they seem to try to get more moderate. When they lose yet again, maybe they will finally shed their left-wing policies and we will get more moderate ones, rather than the pseudo-moderation they pretend to now," he said.

[NOTE: Labour were defeated again in 1992, and they did become more moderate.]